JP4689543B2 - LIGHTING DEVICE, LIGHT CONTROL MEMBER INCLUDING THE SAME, AND IMAGE DISPLAY DEVICE USING THE SAME - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a plate-type light control member, a direct illumination device having a plurality of linear light sources using the plate-like light control member, and an image display device using the same, and in particular, has a large size, high luminance, and uniform luminance. The present invention relates to a lighting device of a direct type that is suitably used for an illumination signage device, a liquid crystal display device, and the like that are required to have high performance, a light control member provided in the illumination device, and an image display device using the light control member.

  An illumination device having a rectangular emission surface is used for an illumination signboard, a backlight of an image display device, and the like. An illumination device having such a rectangular emission surface usually obtains rectangular emission light by making the light from the primary light source uniform within the rectangular emission surface. They usually use an edge light system in which light from the light source placed on the side edge of the light guide plate is guided in the front direction by the light guide plate and is made uniform by the diffusion sheet, and a light source is placed on the back side of the illumination surface, and the light is diffused. There is a direct system that makes it uniform.

The direct type has a tendency to increase the thickness because the light source is provided on the back surface of the apparatus. For this reason, it is advantageous to provide the light source at the side edge in a field where thinness is required such as a mobile phone or a mobile personal computer. The edge-light method is the mainstream.
On the other hand, in recent years, there has been an increasing demand for larger displays and higher brightness mainly in the market of televisions and personal computer monitors. In particular, with the increase in the size of the display, the edge light method reduces the ratio of the length of the peripheral portion where the light source can be arranged to the display area, and the amount of light is insufficient, so that sufficient luminance cannot be obtained.

Therefore, a method has been proposed in which a plurality of films for improving luminance are arranged on a surface light source to improve the light use efficiency (see, for example, Patent Document 1).
However, the brightness enhancement film is not necessarily advantageous from the viewpoint of productivity and thinning because it leads to an increase in cost and the number of films to be used increases. Further, the edge light system has a problem that the weight of the light guide plate increases as the display becomes larger. As described above, in the edge light system, it has been difficult to meet market demands such as an increase in display size and brightness in recent years.

Therefore, a direct method using a plurality of light sources is attracting attention. In this method, the utilization efficiency of light emitted from the light source, that is, the ratio of the light flux emitted from the light emitting surface to the light flux emitted from the light source is high, and the number of light sources can be increased freely. That is, since the amount of light can be increased freely, the required high brightness can be easily obtained, and there is no reduction in brightness or brightness uniformity due to an increase in size. Furthermore, since a light guide plate that directs light to the front is not necessary, the weight can be reduced.
Also, as other lighting devices, for example, lighting signboards, etc., have a simple configuration, and high brightness can be easily obtained without using a film for improving brightness. is there.

  However, the direct system has to solve unique problems such as elimination of lamp image, thinning, and energy saving. In particular, the lamp image appears as brightness unevenness much more remarkable than the edge light method. For this reason, it is difficult to eliminate the lamp image by means conventionally used in the edge light system, that is, means such as a diffusion film in which a diffusion material is applied to the film surface.

Therefore, a diffusion plate containing a diffusion material is widely used. In this method, for example, as shown in FIG. 6, a diffusion plate 6 in which diffusing material fine particles are dispersed inside a transparent flat plate is installed on the front side of a linear light source 1 in which a reflection plate 2 is arranged on the back side. In order to obtain good diffusibility and light utilization efficiency, inorganic fine particles and cross-linked organic fine particles are blended as a diffusing material in base resin such as methacrylic resin, polycarbonate resin, styrene resin, and vinyl chloride resin. Thus, a method for producing a light diffusion plate (for example, see Patent Document 2) has been studied.
However, the method using these diffusing materials is not preferable from the viewpoint of energy saving because the light use efficiency decreases due to the absorption of light into the diffusing material and the diffusion of light in unnecessary directions. Moreover, although a lamp image can be reduced by arranging many light sources close to each other, there is a problem that power consumption increases.

On the other hand, a method of erasing the lamp image by giving the reflector a unique shape has been proposed (see, for example, Patent Document 3). However, it is not preferable because it is necessary to align the shape of the reflector and the light source, and the thickness of the reflector may be hindered due to the shape of the reflector.
Also, a method of installing a reflective member facing the light source (for example, see Patent Document 4), a method of arranging a light beam direction conversion element such as a Fresnel lens for each light source, etc. (for example, see Patent Document 5) However, as in the method described in Patent Document 3, since accurate alignment between the member and the light source is necessary, there arises a problem that productivity is inferior.

In large illuminating devices, the demand for thinning is not strict as compared with mobile phones, mobile personal computers, and the like, so it can be dealt with by shortening the distance between the light source and the diffusion plate or reducing the number of optical films.
In order to realize energy saving, it is necessary to increase the efficiency of light utilization. The direct method can increase the number of light sources as described above, and it is easy to obtain high brightness, but from the viewpoint of energy saving, use of light such as using a large amount of diffusing material to eliminate the lamp image. You must avoid measures that greatly reduce efficiency.

Japanese Patent Laid-Open No. 2-17 JP 54-155244 A Japanese Patent No. 2852424 JP 2000-338895 A JP 2002-352611 A

  An object of the present invention is to improve the front luminance and the luminance uniformity on the exit surface of a direct illumination device having a plurality of linear light sources and an image display device using the same. It is also an object to solve these problems even in a configuration in which the number of linear light sources effective for energy saving is reduced. Another object is to provide a light control member that can solve the above-described problems by providing the lighting device and the image display device. Another object of the light control member is to avoid the use of a diffusing material, which is a factor for reducing the light utilization efficiency, or to significantly reduce the amount of use compared to a conventional diffusing material. Furthermore, it is an object of the present invention to provide a light control member that can be easily incorporated into a lighting device or an image display device without strict alignment. Another object of the light control member is to prevent deterioration in appearance due to damage. Furthermore, it aims at avoiding the coloring by the diffracted light originating in the arrangement | sequence of the fine convex part of these light control members, and preventing the fall of image quality.

In view of the above-mentioned problems, the present inventors have made the following studies and have reached the present invention.
In an illumination device of a type directly below a plurality of linear light sources, the incident energy is high immediately above the linear light sources, and the incident energy is small between the linear light sources. If the convex portion is arranged on the light exit surface side of the light control member and there is an angle of the convex portion slope that acts to direct the light incident from the oblique direction between the linear light sources, the front luminance between the linear light sources is As a result, the ratio with the front luminance directly above the linear light source becomes small, and as a result, the luminance unevenness is eliminated. By devising the convex shape of the light control member, the above problems have been solved.

Further, the present inventors have found that the luminance can be further improved by arranging the second light control member on the light exit surface side of the light control member and optimally designing the convex shape.
The illumination device according to claim 1 has a rectangular emission surface composed of an X direction and a Y direction perpendicular to the X direction, a reflector, a plurality of linear light sources, a plate-like light control member, The reflecting plate is arranged in parallel to the X direction and the Y direction, and the linear light source is arranged in one imaginary plane parallel to the X direction and the Y direction on the exit surface side of the reflecting plate. And the linear light sources are arranged with the longitudinal direction parallel to the Y direction and arranged along the X direction, and the light control member is on the emission surface side of the arranged linear light sources. And the main surface is parallel to the virtual plane on which the linear light sources are arranged, and the main surface of the light control member faces the linear light source and receives light from the linear light source It consists of an entrance surface and an exit surface that emits light received by the entrance surface, and the exit surface has a plurality of bowl-shaped projections on the surface. The protrusion has a hook-shaped ridge line corresponding to the top formed in parallel to the Y direction and arranged along the X direction, and the light control member extends along the X direction and is perpendicular to the main surface. In the cross section cut by the cross section, the maximum inclination angle θ of the convex part is 58 degrees to 80 degrees, and the top part of the convex part in the cross section is the origin and perpendicular to the X direction and toward the incident surface is the Z direction. The illumination device is characterized in that the shape of the convex portion is approximated by the following equation (1) .

The lighting device according to claim 2 is the lighting device according to claim 1, wherein:
−5.031 ≦ K ≦ −0.355
An illumination device characterized by satisfying the above is provided.

  The lighting device according to claim 3 is the lighting device according to claim 1 or 2, wherein a ratio b / a between the width a of the convex portion and the height b of the convex portion in the cross section is 0. Provided is a lighting device characterized by being 35 to 0.8.

  A lighting device according to a fourth aspect is the lighting device according to the first to third aspects, wherein the width a of the convex portion is 10 μm to 500 μm.

  The illuminating device according to claim 5 is the illuminating device according to claims 1 to 4, wherein the light control member has a flat portion at a valley portion of the convex portion. .

  A lighting device according to a sixth aspect is the lighting device according to any one of the first to fifth aspects, wherein the light control member includes a diffusing element.

  The illumination device according to claim 7 is the illumination device according to claim 6, wherein the diffusing element has an embossed shape provided on an incident surface of the light control member. provide.

  The illumination device according to claim 8 is the illumination device according to claims 1 to 7, wherein the refractive index n of the light control member is 1.45 to 1.65. provide.

  The illuminating device according to claim 9 is the illuminating device according to any one of claims 1 to 8, wherein the distance between the centers of any adjacent linear light sources is D, the center of any linear light source and the Provided is an illuminating device in which D / H is 1.8 ≦ D / H ≦ 3.8, where H is a distance from the incident surface of the light control member.

  The illuminating device according to claim 10 is the illuminating device according to any one of claims 1 to 9, wherein the virtual plane is arranged on the emission surface side of the light control member and the linear light source is arranged on the main surface. The second light control member includes a second light control member in parallel with the main surface of the second light control member, an incident surface that receives the light emitted from the light control member, and an output that emits the light received from the incident surface. A plurality of bowl-shaped projections formed on the surface, the projection has a bowl-shaped ridge line corresponding to the top formed in parallel with the Y direction, and along the X direction. In a cross section in which the second light control members are cut along a cross section along the X direction and perpendicular to the main surface, the maximum inclination angle θ of the convex portion is 30 degrees to 80 degrees. An illumination device is provided.

  The illumination device according to claim 11 is the illumination device according to claim 10, wherein the top of the convex portion in the cross section of the second light control member is an origin and is perpendicular to the X direction and the Y direction, and Provided is an illuminating device characterized in that when the direction toward the incident surface is the Z direction, the shape of the convex portion is approximated by the equation (1).

  The illuminating device according to claim 12 is the illuminating device according to claim 10, wherein in the cross section of the second light control member, the shape of the convex portion is a prism shape, and the apex angle ζ is 80. Provided is an illuminating device characterized in that the angle is from 120 degrees to 120 degrees.

  A lighting device according to a thirteenth aspect is the lighting device according to any one of the tenth to eleventh aspects, wherein a convex shape is a hyperbolic shape in the cross section of the second light control member, and the hyperbolic 2 Provided is a lighting device characterized by a hyperbolic shape in which an angle ξ formed by two asymptotes is 30 to 120 degrees.

The illuminating device according to claim 14 is the illuminating device according to claims 10 to 13, wherein the second light control member has a flat portion at a valley portion of the convex portion. I will provide a.
The illuminating device according to claim 15 is the illuminating device according to claims 10 to 14, wherein the second light control member has a texture on the incident surface side. .
The illuminating device according to claim 16 is the illuminating device according to claims 10 to 15, wherein the refractive index n of the second light control member is 1.45 to 1.65. A lighting device is provided.

  The light control member of Claim 17 provides the light control member with which the illuminating device of any one of Claims 1-16 is provided.

  An image display device according to an eighteenth aspect provides an image display device characterized in that a transmissive display element is provided on the exit surface side of the illumination device according to any one of the first to sixteenth aspects.

  The present invention has an effect of directing obliquely incident light to the front by the convex portion arranged on the emission side of the light control member, and has an effect of eliminating luminance unevenness because light is emitted in the front direction between the linear light sources. By optimizing the shape of the convex portion, the lamp image can be eliminated even in a configuration in which the interval between the linear light sources is wide, and a reduction in the number of light sources advantageous for energy saving can be realized. In addition, since the lamp image can be eliminated by optimizing the convex shape, it is possible to avoid the use of a diffusing material or to significantly reduce the diffusing material, thereby reducing light absorption and light emission in unnecessary directions. , Increase the efficiency of light usage and save energy.

  The invention described in claim 1 has a rectangular emission surface composed of an X direction and a Y direction perpendicular to the X direction, and includes a reflection plate, a plurality of linear light sources, and a plate-like light control member. The reflecting plate is arranged in parallel to the X direction and the Y direction, and the linear light source is arranged in one virtual plane parallel to the X direction and the Y direction on the exit surface side of the reflecting plate. And the linear light sources are arranged with the longitudinal direction parallel to the Y direction and arranged along the X direction, and the light control member is arranged on the emission surface side of the arranged linear light sources. And the main surface is parallel to the virtual plane on which the linear light sources are arranged, and the main surface of the light control member faces the linear light source and receives the light from the linear light source. And an exit surface that emits light received by the incident surface, and the exit surface has a plurality of bowl-shaped projections on the surface. The convex portion has a ridge-like ridgeline corresponding to the top portion formed in parallel to the Y direction, and is arranged along the X direction, and the light control member has a cross section along the X direction and perpendicular to the main surface. In the cut cross section, the maximum inclination angle θ of the convex portion is 58 degrees to 80 degrees. When the maximum inclination angle θ of the slope of the convex portion arranged on the light control member emission surface with respect to the emission surface is in the range of 58 degrees to 80 degrees, it is possible to direct light incident from a sufficiently distant position, that is, oblique incident light to the front. Therefore, there is an effect of improving the front luminance between the linear light sources, and uneven luminance can be eliminated. Further, since the obliquely incident light is directed to the front, there is an effect of condensing the light, which leads to an improvement in front luminance. If the maximum inclination angle θ of the convex portion is in the range of 58 degrees to 80 degrees, the above effect can be obtained. When the maximum slope angle is smaller than 58 degrees, the light collecting action is weakened, the front luminance is lowered, and the luminance unevenness is increased. Conversely, when the maximum inclination angle θ is 80 degrees or more, it is not desirable because it becomes difficult to manufacture the mold.

  Moreover, the shape of the convex part in this cross section is represented by the approximate expression (1) of the curve described above. When the cross-sectional shape is represented by a curve, the light emitted from the light control member is directed in various directions, so that a smooth viewing angle characteristic can be obtained and the luminance unevenness is further reduced.

  In the invention according to claim 3, as shown in FIG. 2, the ratio b / a between the width a of the convex portion and the height b of the convex portion is 0.35 to 0.8. When the ratio b / a is small, the resin is easy to enter the mold when the light control member is manufactured, and the manufacturing becomes easy. On the other hand, when the ratio b / a is small, the light condensing performance is lowered, the luminance unevenness is increased, and the optical performance is lowered.

  The invention according to claim 4 is an illumination device in which the width a of the convex portion is 10 μm to 500 μm. When the width of the convex part a is smaller than 10 μm, coloring due to diffracted light occurs, leading to deterioration in quality. Further, when the width a is larger than 500 μm, the streaks of the convex portions are conspicuous, and the quality is also lowered.

  The invention according to claim 5 is characterized in that a flat portion is provided in a valley portion of the convex portion. When the valley portion has a flat portion, when a female die is manufactured by cutting, there is an effect of preventing a fine portion of the die from falling down.

  The invention according to claim 6 is characterized in that the light control member has a diffusing element. There is an effect of further increasing the effect of eliminating luminance unevenness.

  The invention according to claim 7 is characterized in that the light control member has a texture on the incident surface. Providing wrinkles on the incident surface has effects such as preventing appearance defects and making scratches inconspicuous. If the surface roughness due to the embossing is too rough, the resulting diffusibility becomes stronger, and as a result, light may be emitted in an unfavorable direction, leading to a decrease in front luminance. Therefore, it is necessary to provide an embossing with an appropriate roughness.

It is characterized by being. The higher the refractive index, the better the optical performance, and b / a can be kept low as a shape having the same optical performance. However, when the refractive index is high, the material becomes expensive, which is not desirable. Further, when the refractive index is small, sufficient optical performance cannot be obtained. The optimum refractive index is preferably in the range of 1.45 to 1.65.

  In the ninth aspect of the present invention, as shown in FIG. 3, the distance between the centers of any of the adjacent linear light sources is D, the center of the arbitrary linear light source, and the incident surface of the light control member. D / H is 1.8 ≦ D / H ≦ 3.8, where H is the distance. When D / H is large, the number of the linear light sources is reduced and the lighting device is thinned. However, when D / H increases, optical design for eliminating luminance unevenness becomes difficult.

  According to a tenth aspect of the present invention, when the second light control member is disposed on the light exit surface side of the light control member, the second light control member receives the light emitted from the light control member. A projection surface formed on the exit side of the light control member, and the maximum inclination angle θ is 30 degrees to 80 degrees. It is characterized by. When the maximum inclination angle θ of the convex portion is 30 to 80 degrees, there is an effect of condensing light, and the front luminance can be improved. If the slope angle is smaller than 30 degrees, the light condensing effect is lowered, and the luminance improving effect is lowered. On the other hand, when the slope angle is larger than 80 degrees, it becomes difficult to manufacture the mold.

  The invention according to claim 11 is characterized in that the shape of the curved line in the cross section of the second light control member is represented by the formula (1). When the cross-sectional shape is displayed as a curve, the light emitted from the light control member is directed in various directions, so that smooth visual field characteristics can be obtained.

  According to the twelfth aspect of the present invention, in the second aspect, the shape of the convex portion in the cross section of the light control member is a prism shape, and the apex angle ζ shown in FIG. 5A is 80 degrees to 120 degrees. The prism shape means that the ratio of inclined surfaces having an angle is large, and the effect of directing obliquely incident light to the front is large, leading to an improvement in luminance. When the prism apex angle ζ is larger than 120 degrees, the light condensing function is diminished and the effect of improving the luminance is lowered. Conversely, if the prism apex angle ζ is smaller than 80 degrees, the prism tip has a sharp shape, the direction changing action becomes too large, and only the oblique incident light is directed to the front, but most of the light is obliquely directed. This is not desirable because

  According to a thirteenth aspect of the present invention, the cross-sectional shape of the convex portion of the second light control member is a hyperbolic shape, and an angle ξ formed by two asymptotes shown in FIG. It is a degree. When the angle ξ formed by the two asymptotes is too large, the light condensing function is weakened, and the brightness enhancement effect is weakened. On the other hand, when the angle ξ formed by the two asymptotes is too small, the direction of the light is changed too much, so that the ratio of the outgoing light in the oblique direction increases and the front luminance decreases.

  The invention described in claim 14 is characterized in that the second light control member has a flat portion in a valley portion of the convex portion. When the valley portion has a flat portion, when a female die is manufactured by cutting, there is an effect of preventing a fine portion of the die from falling down.

  The invention described in claim 15 is characterized in that the second light control member has a texture on the incident surface side. Providing wrinkles on the incident surface has effects such as preventing appearance defects and making scratches inconspicuous. If the surface roughness due to the embossing is too rough, the resulting diffusibility becomes stronger, and as a result, light may be emitted in an unfavorable direction, leading to a decrease in front luminance. Therefore, it is necessary to provide an embossing with an appropriate roughness.

  The invention described in claim 16 is characterized in that the refractive index n of the second light control member is 1.45 to 1.65. The higher the refractive index, the better the optical performance, and b / a can be kept low as a shape having the same optical performance. However, when the refractive index is high, the material becomes expensive, which is not desirable. Further, when the refractive index is small, sufficient optical performance cannot be obtained. The optimum refractive index is preferably in the range of 1.45 to 1.65.

  The light control member according to claim 17 has high brightness uniformity even in a configuration in which the number of light sources that is high brightness and advantageous for energy saving is reduced, which is a feature of the lighting device according to any one of claims 1 to 16. The light control member which can implement | achieve is provided.

  Here, the light control member also includes a second light control member that can be included in the illumination device and the image display device of the present invention. By using a plurality of light control members of the present invention, effects such as improvement of effects and light control in a plurality of directions occur. When a plurality of light control members of the present invention are used, these may have the same shape or different shapes. If it is the same shape, productivity will become high. Further, if a combination of different shapes is used, more precise light control is possible.

  In addition, the light control member can realize high performance such as improvement of front luminance, elimination of a lamp image, and control of a viewing angle even when used in a direct type illumination device of another configuration, other than the configuration of the illumination device of the present invention. It can also be used for the configuration of Examples of configurations other than this configuration include a configuration of a single fluorescent tube, a configuration of an illumination device in which light control members are provided on both sides of the fluorescent tube, or a configuration of an illumination device using a U-shaped fluorescent tube as a light source. Is mentioned.

  The image display device according to claim 18 is provided with a transmissive display element on the exit surface side of the illumination device according to any one of claims 1 to 16, thereby providing high brightness and energy saving, and image quality. High image display device can be obtained.

The present invention has a rectangular emission surface composed of an X direction and a Y direction perpendicular to the X direction, and includes a reflection plate, a plurality of linear light sources, and a plate-like light control member. Are arranged in parallel to the X direction and the Y direction, the linear light source is arranged in one virtual plane parallel to the X direction and the Y direction on the exit surface side of the reflector, and The linear light sources are arranged in the longitudinal direction parallel to the Y direction and arranged along the X direction, the light control member is arranged on the emission surface side of the arranged linear light sources, and The main surface is parallel to the virtual plane on which linear light sources are arranged, and the main surface of the light control member is an incident surface that faces the linear light source and receives light from the linear light source, and the incident surface And a plurality of bowl-shaped projections formed on the surface, the projections being apexes. And ribbed ridges are formed in parallel in the Y direction, corresponding to, and arranged along the X direction, in a cross section taken along along and in the main surface and a cross section perpendicular to the light control member in the X direction, The maximum inclination angle θ of the convex portion is 58 degrees to 80 degrees, and the convex portion when the apex of the convex portion in the cross section is the origin, the direction perpendicular to the X direction and the direction toward the incident surface is the Z direction. The shape is approximated by the expression (1) above, and the ratio b / a between the width a of the convex portion and the height b of the convex portion is 0.35 to .0. 8 is preferred . FIG. 2 shows the relationship between the width a of the convex portion and the height b of the convex portion. In the formula (1), it is preferable that −5.031 ≦ K ≦ −0.355 is satisfied.

  FIG. 3 is a sectional view showing the arrangement of the light control member 2, the second light control member 5, and the linear light source 1. In the drawing, the relationship between the distance D between the centers of any adjacent linear light sources and the distance H between the center of any linear light source and the incident surface of the light control member 2 is shown. The lighting device of the present invention is characterized in that D / H is 1.8 ≦ D / H ≦ 3.8, but as the ratio D / H is increased, the convexity of the light control member having the effect of eliminating the uneven brightness is increased. The ratio b / a between the width a of the portion and the height b of the convex portion is increased. This is because as the ratio D / H increases, the proportion of incident light increases from an oblique angle, and the angle of the slope of the convex portion for directing incident light to the front increases, so that the convex portion height is relatively high. As a result, the ratio b / a optimum for eliminating the luminance unevenness increases. For example, when 1.8 ≦ D / H ≦ 2.5, the optimum b / a is 0.35 ≦ b / a ≦ 0.6, and when 2.5 ≦ D / H ≦ 3.5, the optimum b / a is optimum. b / a is 0.5 ≦ b / a ≦ 0.7. When 3.5 ≦ D / H ≦ 3.8, the optimum b / a is 0.6 ≦ b / a ≦ 0.8. .

  Further, a second light control member may be provided on the light exit surface side of the light control member. When the second light control member is provided, the second light control member is disposed on the light emission surface side of the light control member, and the main surface is parallel to the virtual plane on which linear light sources are arranged. The second light control member includes an incident surface that receives light emitted from the light control member, and an output surface that emits light received from the incident surface, and the emission surface has a bowl shape on the surface. A plurality of protrusions are formed, and the protrusions have hook-shaped ridgelines corresponding to the tops formed in parallel to the Y direction and arranged along the X direction.

  The maximum inclination angle of the convex portion of the second light control member is 30 to 80 degrees. The shape of the convex portion is a prism shape, an elliptical shape, a hyperbolic shape, or the like. When the shape of the convex portion is a prism shape, the maximum inclination angle of the convex portion is desirably 30 ° to 50 °, and when the shape of the convex portion is a hyperbolic shape, the maximum inclination angle of the convex portion is 40 ° to 70 °. Desirably, the maximum inclination angle of the convex portion is preferably 50 to 80 degrees when the convex portion has an elliptical shape.

  When the shape of the convex portion is a prism shape, the apex angle ζ of the prism shown in FIG. 5A is preferably 80 degrees to 120 degrees, more preferably 90 degrees to 115 degrees, It is further desirable that the angle is 100 degrees to 110 degrees.

  When the shape of the convex portion is a hyperbolic shape, the angle ξ formed by the two asymptotes shown in FIG. 5B is preferably 30 to 120 degrees, and the angle ξ formed by the two asymptotes is large. When too large, the light condensing effect becomes weak, and the brightness enhancement effect becomes weak. On the other hand, when the angle ξ formed by the two asymptotes is too small, the direction of the light is changed too much, so that the ratio of the outgoing light in the oblique direction increases and the front luminance decreases.

  The reflectance of the reflecting plate 4 arranged on the back surface in parallel with the X direction and the Y direction is preferably 80% or more, and the higher the light utilization efficiency, the more desirable. By reflecting the light traveling from the linear light source 1 to the back surface and the light reflected by the light control member 2 and traveling toward the back surface further to the emission side, the light can be used effectively, so that the light utilization efficiency is increased. Examples of the material of the reflecting plate include metal stays such as aluminum, silver, and stainless steel, white coating, and foamed PET resin. A reflector having a high reflectance is desirable for improving the light utilization efficiency. From this viewpoint, silver, foamed PET resin, and the like are desirable. Further, it is desirable to diffuse and reflect light in order to improve the uniformity of the emitted light. From this viewpoint, foamed PET resin and the like are desirable.

  Also, the linear light source is the most common light source for these lighting devices because it is easier to eliminate luminance unevenness than the point light source and the wiring is short and easy. A cold cathode tube or the like is often used as the linear light source. In general, it is advantageous for production to use the same type of linear light source, and it is also advantageous for uniform brightness. In this case, however, the linear light source is oriented parallel to the long side of the output surface rectangle. It is desirable that the number of linear light sources can be reduced. Also, when linear light sources are arranged at equal intervals in the same plane, the luminance unevenness that is a problem becomes periodic with the arrangement of the linear light sources, and the light diffuser plate with uniform optical performance in the main surface It is desirable because it is easy to eliminate luminance unevenness. The reflector is not essential, but it works to reflect the light emitted from the linear light source and the light diffusing plate opposite to the exit direction to the exit side and use it again as the exit light. It is advantageous.

Here, as shown in FIG. 3, the second light control member having the thickness T ′ is placed on the first light control member having the thickness T, and the second light control member is formed by the first light control member. It is possible to adopt a configuration that supports In this case, the thickness T of the first light control member 2 is desirably 1 mm to 5 mm, and the thickness T ′ of the second light control member is desirably 0.2 mm to 1 mm.
If the thickness T of the light control member 2 is small, the thickness of the light control member becomes thin and the thickness of the lighting device is also thin, which is desirable. However, if the light control member 2 is too thin, the strength of the light control member will be weak. Luminance unevenness in the front direction occurs. In addition, the mechanical strength may be weakened and may be damaged. Particularly for large-sized displays, mechanical strength is required, and 2 mm to 5 mm is desirable. On the other hand, if the thickness is too large, the thickness of the lighting device is increased, which is not desirable because it is contrary to the demand for thickness reduction. From the viewpoint of thinning, it is desirable to be 1 mm to 3 mm.

  Since the second light control member is disposed on the light exit surface side of the light control member 2, it is not necessary to support it and the deflection to the light source side can be avoided, so the thickness T ′ of the first light control member is the light It can be made thinner than the thickness T of the control member. In addition, when using a flexible material such as rubber reinforced MS as a material, it is desirable to avoid the risk of breakage. However, if it is thinner than 0.2 mm, it may cause wrinkles. -1 mm is desirable.

  The width of the convex portions formed on the light emission surfaces of the light control member and the second light control member is desirably 10 μm to 500 μm. When the thickness is larger than 500 μm, the streak that is the ridge line of the convex portion is easily confirmed when the exit surface is observed, and the quality is deteriorated. On the other hand, when the thickness is smaller than 10 μm, coloring occurs due to the diffraction phenomenon of light, and the quality deteriorates. Furthermore, in the image display device of the present invention in which the transmissive liquid crystal panel is provided as the transmissive display device element, the width a of the convex portion in the X direction is 1/100 to 1 / 1.5 of the pixel pitch of the liquid crystal. It is desirable. If it is larger than this, moire occurs with the liquid crystal panel, and the image quality is greatly reduced.

  In addition, it is advantageous to provide a flat portion in the convex valley portion because the convex portion of the mold is difficult to deform. In particular, when the convex portion maximum inclination angle θ is 70 degrees or more, it is desirable to provide a flat portion. If the maximum inclination angle θ is less than that, it may not be provided. When the maximum inclination angle θ is large, it is desirable to provide a flat portion of the valley portion because the tip of the die becomes thin when the female die is cut and there is a risk of falling.

  The light control member or the second light control member has a texture on the incident surface. Providing wrinkles on the incident surface has effects such as preventing appearance defects and making scratches inconspicuous. However, if the surface roughness due to embossing is too rough, the diffusibility due to this increases, and as a result, light may be emitted in an unfavorable direction, leading to a decrease in front luminance. It is necessary to provide a grain having an appropriate roughness.

  The light control member or the second light control member has a refractive index n of 1.45 to 1.65. The higher the refractive index, the better the optical performance, and b / a can be kept low as a shape having the same optical performance. In order to obtain optical performance, the refractive index is desirably 1.55 to 1.65. However, when the refractive index is high, the material becomes expensive, which is not desirable. Further, when the refractive index is small, sufficient optical performance cannot be obtained. The refractive index when a general material is used is 1.45 to 1.60.

  Due to the inclination angle of the convex part of the light control member, it is possible to obtain sufficient brightness even between linear light sources by directing obliquely incident light to the front. can do. Examples of the diffusing element herein include a diffusing material coated on the incident surface and / or the emitting surface, and a random diffusing material provided on the incident surface and / or the emitting surface and / or a diffusing material dispersed inside.

  The formation of random irregularities can be realized by applying a solution in which fine particles are dispersed to the main surface or transferring from a mold having irregularities. As for the degree of unevenness, the arithmetic average roughness Ra is desirably 3 μm or less. If it becomes larger than this, the diffusion effect becomes too large, and the front luminance is lowered. When the incident surface is flat, light incident from various directions is condensed to some extent near the front due to refraction at the incident surface when entering the light control member. As a result, the light emission ratio in the front direction is increased. Increase. For example, when the refractive index of the light control member is 1.55, the light is condensed in an angle range within 40 degrees with respect to the normal direction of the incident surface. When unevenness is given to the incident surface, the light incident on the light control member is refracted at a wide angle and proceeds, so that the effect of increasing the light emission ratio in the front direction may be reduced. Moreover, when providing a fine unevenness | corrugation in an output surface, the effect which increases the light emission ratio to a front direction by an unevenness | corrugation similarly may be reduced by being refracted by an uneven surface. It can be adjusted to a range desired for the intended use from the balance between the obtained diffusibility and luminance unevenness eliminating effect and front luminance.

  In the case where fine particles that diffuse light are provided inside the structure, the concentration of the fine particles can be kept very low compared to a normal diffusion plate. Any material used for a fine particle diffusion plate or the like can be preferably used. The preferred concentration of fine particles varies depending on the material, and examples thereof include dispersing 0.4% by weight of siloxane polymer particles in a methyl methacrylate-styrene copolymer.

  In addition, a transparent support substrate made of resin, glass, or the like may be provided on the light source side of the light control member or the second light control member. By disposing the support substrate, the light control member can be supported even if the light control member is thinned, for example, from 0.1 mm to 1 mm. By reducing the thickness of the light control member, molding by extrusion molding or the like is further facilitated, and productivity is improved. In addition, it becomes easy to support the light control member that becomes increasingly difficult as the surface light source element becomes larger. The thickness of the support substrate is not particularly limited, but is usually from 0.5 mm to 5 mm. When the support substrate is made of a rigid material such as glass, it is usually about 0.5 mm to 2 mm for light weight and strength. In the case of a lightweight material such as a thermoplastic resin, it is more preferably in the range of 2 mm to 4 mm. Similar to the light control member, the support substrate may be improved in diffusibility by dispersing fine particles for diffusing light therein, embossing on the surface, or applying fine particles. In the case of dispersing fine particles inside or embossing on the surface, it is preferable for production that the base material is a thermoplastic resin, and a suitable material is equivalent to the light control member. Further, the support substrate may be joined to the light control member provided in an overlapping manner, for example, it can be joined with a transparent adhesive or the like, thereby simplifying the assembly process of the surface light source element, and further provided in an overlapping manner. The light control member can be prevented from shifting and wrinkling.

  The method for measuring the inclination angle of the convex portion in the cross section of the light control member or the second light control member is to cut the light control member or the second light control member in the cross section and take a photograph with an optical microscope. There is a way to measure the angle. As a more accurate measurement method, there is a method of taking a photograph with an SEM (scanning electron microscope) and measuring an angle.

  Examples of the method for manufacturing the light control member or the second light control member include extrusion molding, injection molding, and 2P molding using an ultraviolet curable resin. The size of the convex portion, the shape of the convex portion, mass productivity, etc. A suitable molding method may be selected in consideration. Extrusion molding is suitable when the main surface is large.

  It is desirable that the convex portions of the light control member or the second light control member have the same shape. Since the optical properties of the light control member are uniform, alignment is not necessary, and it is possible to immediately respond to changes in the display size, the number of linear light sources and the arrangement, and the lighting device can be manufactured with high productivity. .

  The light control member can be desirably used as long as it is a material usually used as a base material of an optical material, and usually a light-transmitting thermoplastic resin is used. For example, methacrylic resin, polystyrene resin, polycarbonate resin, cycloolefin resin, methacryl-styrene copolymer resin, cycloolefin-alkene copolymer resin and the like can be mentioned.

  As the material of the second light control member, any material that is usually optically transparent can be used. For example, methacrylic resin, polycarbonate resin, cycloolefin resin, polystyrene resin, methacryl-styrene copolymer resin, cycloolefin -Alkene copolymer resin, rubber reinforced MS, etc. are mentioned.

  The image display device of the present invention is realized by a method such as using a transmissive liquid crystal display element on a lighting device, and is not particularly limited, but the transmissive display element includes a transmissive liquid crystal panel, An image display device having excellent display surface luminance uniformity can be obtained. Here, the image display device refers to a display module in which a lighting device and a display element are combined, and a device having at least an image display function such as a television or a personal computer monitor using the display module.

Examples of the present invention will be described below, but the present invention is not limited thereto.
This embodiment is evaluated by measuring the front luminance and luminance uniformity of a lighting device including the light control member of the present invention. The results are summarized in Table 1.

First, production of a light control member used in the examples will be described.
Of the two light control members of the present invention provided in the lighting device of Example 1, the light control member disposed closer to the linear light source is produced by the following method. By cutting the entire surface of the roll mold, the groove-shaped recesses of the light control member to be produced are inverted with the ridge-shaped protrusions with a width of 0.300 mm in parallel, and flat with an interval of 0.004 mm. A large number of molds are provided across the section to form a shaping roll mold. Polystyrene (HRM40 refractive index 1.59 manufactured by Toyo Styrene Co., Ltd.) is extruded using the above roll mold to form a shaped sheet having a thickness of 1.5 mm in the Z-axis direction. Are cut into a length of 200 mm and a length in the Y-axis direction of 360 mm to obtain a light control member. Similarly, the light control member of Examples 3, 5-7, and 18 and the light control member disposed closer to the linear light source among the two light control members provided in Examples 4, 8, and 19 Is made.

  Of the two light control members of the present invention provided in the illumination device of Example 2, the light control member disposed closer to the linear light source is produced by the following method. In order to obtain the convex shape of the light control member of the present invention, a groove having a width of 0.100 mm and having a shape obtained by inverting the hook-shaped convex portion of the light control member to be created on the entire surface of the metal plate by cutting. A large number of concave portions are provided in parallel with a flat portion of 0.002 mm between them to form a shaping die. Thereafter, a shaping plate having a convex portion on one surface is prepared with an ultraviolet curable resin using the molding die obtained, and a stamper is produced by electroforming nickel on the surface having the convex portion. Polystyrene (G100C refractive index 1.59 manufactured by Toyo Styrene Co., Ltd.) is injection-molded using the stamper, so that the thickness in the Z-axis direction is 2 mm, the length in the X-axis direction is 200 mm, and the length in the Y-axis direction is 360 mm. A control member is produced. Similarly, the light control member disposed in the direction closer to the linear light source among the light control members of Examples 9 and 16 and the two light control members included in Examples 10 to 15 and 17 is manufactured.

Next, of the two light control members of the present invention provided in the illumination devices of Examples 1, 2, 4, 8, 10-15, 17, and 19, the second light disposed farther from the linear light source. The control members I to VI are produced by the following method.
The second light control member I of the present invention is a groove having a shape obtained by reversing the 80 μm wide ridge-shaped convex portion of the second light control member to be formed on the entire surface of the roll-shaped mold by cutting. By forming the concave portions in parallel with a flat portion of 0.05 mm in between, a forming roll-shaped mold is obtained. Using the above-described shaping roll mold, a methyl methacrylate-styrene copolymer resin (refractive index 1.54) is extruded to produce a shaped sheet having a thickness of 0.5 mm in the Z-axis direction. To do. This is cut into a length of 200 mm in the X-axis direction and a length of 360 mm in the Y-axis direction to obtain a light control member. Similarly, the second light control member II is created.

The second light control member III is produced by the following method. The convex portion formed on the emission surface is formed by using a mold in which groove-shaped concave portions having a width of 80 μm are continuously formed in parallel by cutting. An ultraviolet curable resin having a refractive index of 1.55 is applied to the cutting surface of the mold, and a transparent material having a refractive index of 1.55, a length of 200 mm, a width of 360 mm, and a thickness of 1 mm, which is a methyl methacrylate-styrene copolymer. A light control member is obtained by stacking resin plates and irradiating ultraviolet rays from above the transparent resin plates to cure the ultraviolet curable resin. Similarly, the second light control members IV to VI are manufactured.
Here, the shapes of the convex portions of the light control members other than the light control members III and IV and the second light control member are approximated by the following formula (1). The coefficients C, K, A ₄ , A ₆ , A ₈ , A ₁₀ are shown in Tables 1 and 2 below.

The shapes of the light control members III and IV are approximated to isosceles triangles.

  The structure of the illuminating device of Example 1, 2, 4, 8, 10-15, 17, 19 of this invention is shown in FIG. The configuration of the illumination device of another embodiment is obtained by removing the second light control member from FIG. In FIG. 4, the diffusion sheet is not shown. In carrying out the present invention, a backlight unit is produced. A rectangular shape having a length of 200 mm in the X direction, a length of 360 mm in the Y direction, a length of 25 mm in the thickness direction perpendicular to the X direction and the Y direction, a length of 190 mm in the X direction on the output side, and a length of 350 mm in the Y direction. A rectangular parallelepiped white ABS resin housing having an opening is prepared. The height of the rectangular opening is 18.7 mm. A reflection sheet made of foamed PET resin and having a reflectance of 95% is attached so as to cover the bottom portion to obtain a reflection plate.

  Next, a linear light source is arranged in parallel with the reflecting plate with an interval of 2 mm on the exit side of the reflecting plate. As the linear light source, a plurality of cold cathode tubes having a diameter of 3 mm and a length of 360 mm are arranged along the X direction and parallel to the Y direction. Six cold cathode tubes are arranged at intervals of 28.8 mm. H from the center of the linear light source 1 to the light control member 2 is 15.2 mm, and the distance D between the centers of the adjacent linear light sources 1 is 31.8 mm.

  In all the examples, a diffusion sheet BS-700 (manufactured by Eiwa Co., Ltd.) is disposed between the light control member and the second light control member as the light diffusion means. About Example 1-2, Example 4, Example 8, Examples 10-15, and Examples 17-18, toward a front direction, a reflecting plate, a linear light source, a light control member, a diffusion sheet, 2nd The light control member is arranged and measurement is performed. In other examples, a reflector, a linear light source, a light control member, and a diffusion sheet are arranged in the front direction, and the front luminance and luminance uniformity are measured.

  As a comparative example, the front luminance when a diffusion sheet BS-700 (manufactured by Eiwa Co., Ltd.) is disposed on the exit surface side of a diffuser plate having a total light transmittance of 60% in which diffuser fine particles are dispersed in a transparent resin substrate And measurement of luminance uniformity.

  For the measurement of the front direction and luminance uniformity, the measurement distance is fixed with a luminance meter BM-7 (manufactured by Topcon Technohouse Co., Ltd.), and the vicinity of the center of the backlight is arranged in the direction of the linear light source from the direction perpendicular to the emission surface. And 35 mm (36 points) at 1 mm intervals. The average value of luminance is the front luminance, and the minimum luminance value / maximum luminance value × 100 (%) is the luminance uniformity. Here, the value of the front luminance in Table 1 is shown as a relative value when the measurement result in the comparative example is 100%.

  As a comparative example, in a configuration in which one flat particle diffusion plate having a total light transmittance of 60% is arranged instead of the light control member, luminance uniformity is low and high front luminance cannot be obtained.

  In addition, a liquid crystal panel is arranged so as to cover the emission surfaces of the lighting devices of Examples 1 to 19 and the comparative example, and the image display device of the present invention is obtained. When the obtained images are visually confirmed, the image display device of the comparative example has a large luminance unevenness and a dark screen for all the examples.

It is a schematic block diagram which shows one Example of the illuminating device of this invention. It is a figure which shows the cross section of the convex part of the light control member of this invention. It is a figure which shows ratio D / H of the distance D between the adjacent linear light sources of the illuminating device of this invention, and the distance H with the said incident surface of the said light control member. It is a schematic block diagram which shows another Example of the illuminating device of this invention. It is a figure explaining angle ξ formed by two asymptotic lines of a hyperbola representing a vertex angle ζ and a convex section of the prism in the present invention. It is an example of the structure of the prior art using a flat plate fine particle mixing diffusion plate.

Explanation of symbols

1: linear light source, 2: light control member, 3: convex portion, 4: reflector, 5: second light control member, 6 diffusion plate

Claims (18)

It has a rectangular exit surface composed of an X direction and a Y direction perpendicular to the X direction,
A reflector, a plurality of linear light sources, and a plate-like light control member;
The reflector is arranged in parallel to the X direction and the Y direction,
The linear light source is disposed in one imaginary plane parallel to the X direction and the Y direction on the exit surface side of the reflector,
And the linear light source has a longitudinal direction arranged parallel to the Y direction,
And it is arranged at equal intervals along the X direction,
The light control member is disposed on the emission surface side of the arranged linear light sources, and the main surface is parallel to the virtual plane in which the linear light sources are arranged,
The main surface of the light control member is composed of an incident surface that faces the linear light source and receives light from the linear light source, and an output surface that emits light received by the incident surface,
The emission surface has a plurality of ridge-shaped projections on the surface,
The convex portion has a bowl-shaped ridge line corresponding to the top portion formed in parallel to the Y direction, and arranged along the X direction,
In section cut along and in the main surface and a cross section perpendicular to the light control member in the X direction, the maximum inclination angle θ of the convex portion, Ri 58 to 80 degrees der,
Illumination characterized in that the shape of the convex portion is approximated by the following equation (1) when the top of the convex portion in the cross section is the origin, the direction perpendicular to the X direction and the direction toward the incident surface is the Z direction. apparatus.
The lighting device according to claim 1, wherein:
−5.031 ≦ K ≦ −0.355
A lighting device characterized by satisfying It is an illuminating device of Claim 1 or 2 , Comprising: Ratio b / a of the width a of this convex part in the said cross section and the height b of this convex part is 0.35-0.8. A lighting device. It is an illuminating device of any one of Claims 1-3, Comprising: The width | variety a of this convex part is 10 micrometers-500 micrometers, The illuminating device characterized by the above-mentioned.   It is an illuminating device of any one of Claims 1-4, Comprising: The said light control member has a flat part in the trough part of a convex part, The illuminating device characterized by the above-mentioned.   6. The lighting device according to claim 1, wherein the light control member includes a diffusing element. 7.   The lighting device according to claim 6, wherein the diffusing element has a textured shape provided on an incident surface of the light control member.   It is an illuminating device of any one of Claims 1-7, Comprising: The refractive index n of the said light control member is 1.45 to 1.65, The illuminating device characterized by the above-mentioned.   It is an illuminating device of any one of Claims 1-8, Comprising: The distance between the centers of the arbitrary said linear light sources which adjoin is D, the center of the arbitrary said linear light sources, and the said light control member An illumination device, wherein D / H is 1.8 ≦ D / H ≦ 3.8, where H is a distance from the incident surface. It is an illuminating device of any one of Claims 1-9, Comprising: It is 2nd in parallel with the said virtual plane in which the linear light source has arranged the main surface on the output surface side of the said light control member. A light control member
The main surface of the second light control member consists of an incident surface that receives light emitted from the light control member, and an emission surface that emits light received from the incident surface,
The exit surface has a plurality of hook-shaped protrusions formed on the surface, and the protrusions have hook-shaped ridgelines corresponding to the top formed in parallel to the Y direction and arranged along the X direction,
In the cross section obtained by cutting the second light control member along the X direction and perpendicular to the main surface, the maximum inclination angle θ of the convex portion is 30 degrees to 80 degrees.   The lighting device according to claim 10, wherein the top of the convex portion in the cross section of the second light control member is an origin, and a direction perpendicular to the X direction and the Y direction and toward the incident surface is a Z direction. In this case, the illumination device is characterized in that the shape of the convex portion is approximated by the equation (1).   11. The illumination device according to claim 10, wherein in the cross section of the second light control member, a shape of the convex portion is a prism shape, and an apex angle ζ thereof is 80 degrees to 120 degrees. Lighting device.   12. The lighting device according to claim 10, wherein, in the cross section of the second light control member, a shape of a convex portion is a hyperbolic shape, and an angle ξ formed by two asymptotic lines of the hyperbola is 30 degrees. A lighting device characterized by a hyperbolic shape of ˜120 degrees.   14. The lighting device according to claim 10, wherein the second light control member has a flat portion at a valley portion of the convex portion.   15. The lighting device according to claim 10, wherein the second light control member has a wrinkle on the incident surface side.   16. The lighting device according to claim 10, wherein a refractive index n of the second light control member is 1.45 to 1.65.   The light control member with which the illuminating device of any one of Claims 1-16 is provided.   An image display device comprising a transmission type display element provided on the light exit surface side of the illumination device according to claim 1.